Improvement in pavements



117285 MNTED JUL251871 N EWM@ Un-iran Sira'rns ISAAC H. HOBBS, OFPHILADELPHIA, PENNSYLVANIA.

IMPROVEMENT IN PAVEMENTS.

Specification forming part of Letters Patent No. 117,286, dated July525, 1871.

To all @cham 'it may concern:

Be it known that I, ISAAC H. Horns, of the city and county ofPhiladelphia and State of Pennsylvania, have invented certa-in new anduseful Improvements in Pavements for Streets; and I hereby declare thefollowing` to be a full, clear, and exact description thereof, referencebeing had to the accompanying drawing and to the letters of referencemarked thereon.

The object of my invention is to furnish7 at a moderate cost, a pavementconstructed upon such principles and resting upon such a foundationasshall secure absolute firmness and solidity of structure, evenness ofwear, and consequent freedom from ruts, indentations, and inequalitiesof surface, increased durability, and facility of removal and repair fornecessary excavations in and under the street, and for the introductionof horse-railroads without disturbing the substrata, as there issufficient space above the stone, slag, or cobble foundation and theconcrete illing thereupon to admit of the stringers and other tiesnecessary to their construction being laid directly thereon.

One of the principal difficulties heretofore attending the use of woodenpavements7 when constructed in any of the ordinary methods, has been thetendency to form depressions and inequalities upon the surfaceconsequent upon the rotting or giving way of the foundation upon whichsuch pavements rest. To obviate this, and to produce a pavement whichshall meet all possible exigencies of weather, climate, and wear, aswell as to afford relief' from the annoyance of frequent repairsoriginating in the imperfect methods of construction generally employed,after the street has been properly graded I construct a foundation ofbroken rock, Cobble-stone,

or slag, and upon this, either with or without the intervention ofcement or concrete, arrange the wooden pavement embodying theimprovements herein described, thus uniting the durability of the formerwith the smoothness, elasticity, noiselessness, and cleanliness of thelatter.

Figure l represents a plan of a pavement embodying my invention. Fig. 2is a vertical longitudinal section of he same .as shown at A in Fig. l.Fig. 3 represeg-side and end view of blocks of the shape comme ly used.Fig. 4 is an end view of the concrete mldings as shown at D in Fig. l. i

In constructing the foundation for the pavement, after the street hasbeen properly graded, I prepare a layer of gravel or coarse sand, F, eX-tending over the entire surface ofthe street, be-

tween the ciu'bstones E E, as shown in Fig. l.

Upon and in this is arranged and rnily embedded the broken rock, cobble,or slag foundation, as at I I. This foundation is then pounded or rammeddown with ordinary rammers constructed for that purpose, until itpresents a perfectly regular surface ofthe required arch or curv aturefor the street. Upon this is placed. a layer of cement, H, from one anda half to three inches in thickness, or of concrete composed ofcoalashes, pebbles, or broken stone, to which is added a suflicientquantity of mineral or vegetable tar to give it the requisiteconsistency and to unite the whole into one mass. It is then firmlyrammed down upon and into the interstices below, and smoothly rolledover, preserving' at the same time the proper conveXity of surface forthe street.

It is not absolutely necessary for the purposes of my invention thatthis layer of cement or concrete should be placed upon the rock or slagfoundation and intervene between it and the wooden blocks above,although I greatly prefer it. But a good and very durable pavement maybe made by laying the block directly upon such foundation without theintervention of the concrete or cement.

Upon the foundation constructed as above described I lay the woodenpavement composed' of blocks of the requisite length, thickness, andshape, and which, for the greater durability of the same, are kyanized.ln the pavement as shown at A in Fig. l the sides of the blocks areeither parallel or chamfered, sloped or beveled oft' on one or bothsides, from about the middle of the same to the upper end of each block,until the thickness at the top is reduced about one inch less than atthe bottom, as shown in Fig.2. A concrete, composed of gravel, brokenstone, coal-ashes, sand, and tar, or other like material, in any of theknown and most approved methods and proportions, is then made andcompressed into suitable molds of about a yard or any convenient lengthfor the purpose required, and the moldings then taken out and eitherwholly or partially dried. lhese are of the same height as the blocks,and of the requisite thickness to effect a separation of the rowsthereof from each other to the extent desired, and of a shapecorresponding thereto. When the blocks are beveled off at the top themoldings are made correspondingly wider at that end, and form from themiddle of the same, or thereabout, upward, a wedge or semi-wedge shape,as shown at D in Figs. l and 2, and also in Fig. 4. And when the sidesof the blocks are parallel the sides of the moldings are parallel also,the object of which correspondence in shape is that they may it closelybetween the rows of blocks. The blocks are then arranged endwise in rowsacross the street, with the grain of the wood set vertically thereon,and interposed between each row thereof are these concrete moldings.After a large number of these alternating rows of blocks and moldingshas been thusarranged, as closely compressed together as possible, themoldings are then rammed down solidly between the blocks, until itbecomes a tight packing, and forms not only a water-tight separationbetween each row, but also wedges the entire mass closely together. Theremaining interstices, if any, may then be filled with concrete, orgravel and tar, or other like substances, in the ordinary manner.

Pavements constructed according to the principles embodied herein arenot only unaffected by any and all the contingencies of climate andWeather, and inpervious alike to rain, moisture, and the action offrost, and their durability and usefulness immensely increased by thewatertight foundation upon which the blocks rest, and the concretepacking between the separate rows thereof, but also the rapidity andfacility with which such pavements can be laid down are greatlyincreased, the cost of their construction cheapened by the diminishedamount of wood required, and which at the same time affords the greatadditional advantage of securing a firmer footing for the feet ofpassing animals so long as the pavement shall last. Another greatadvantage which my pavement possesses arises from the fact that inrepairing many streets where cobble or other stone has been used thematerial for the foundation is directly at hand, thereby cheapening thecost of such pavements.

Having thus described my invention, what I claim, and desire to secureby Letters Patent, is The construction of a wooden pavement by placingconcrete moldings between each row of blocks of a size and shapecorresponding thereto and of any desired thickness, in combination withthe Cobble-stone, slag, or rock foundation, and the cement or concretefilling or layer thereupon, substantially in the manner and for thepurpose hereinbefore set forth.

. ISAAC H. HOBBS. Witnesses:

W. B. POWELL, B. CLIFFORD DicKsoN.

